Axially centered recoil mechanism for machine guns



Jan. 6, 1942. J w WHITE "2,269297 AXIALLY CENTERED RECOIL MECHANISM FORMACHINE GUNS Filed Jan. 22, 1940 2 Sheets-Sheet l INVENTOR.

BY John W M/h/fe.

ORNEY.

J. w. WHITE 2,269,297

AXIALLY CENTERED RECOIL MECHANISM FOR MACHINE GUNS' Jan. 6, 1942.

Filed Jan. 22, 1940 2 Sheets-Sheet 2 i .VIIIIIIIIIIIIIII:

v INVENTOR. JOhn W. Whi 72 RNEY.

Patented den. 6, 142 i I 9&2

sir :1.

I AXIALLY CENTER-ED REfiOEL MECHANISM FOR MACNE GUN S John W. White,Burbank, (Jalifi, assignor to Bendix Aviation Corporation, South Bend,End, a corporation of Delaware Application January 22, 1940, Serial No.314,902

3 Claims. (01. 89-42) This invention relates to recoil mechanisms, iouscylinders and sleeves by forming and seand more particularly to recoilmechanisms for curing together parts made of stampings and machine gunsin airplane use. sections of tubing, rather than boring them out Oneimportant governing consideration for of solid forgi gs and Cast s u t eall any device used in aircraft is weight. The ob- 5 members are aslight and thin as Possible in ject must be as light as possible. Anoth rnview of the service requirements. The lightness sideration arising fromuse with armament is of e asse b y of the various p s is due in that thedevice must be reliable. To this end p r also o t use of hydrogenwelding where y the working parts must be few and simple and 110 Weldbeads a left on the materialdesigned to minimize service trouble. Afurther The particular recoil unit lll ow in d t consideration inaircraft use is that a gun recoil in Figu es 2 a d 3 a d 4 s fo d byattaching mechanism must be so placed with relation to a cylindricalsleeve 2G to he n piece 26 of the recoil forces that couples and forcestranst e un s sleeve ntains a O s t y mltted to the airplane will notafiect the operdrical Portion j e the gun O y- A \ClOse ation andnavigation of th aircraft fitting recoi l sleeve 28 adapted to slide onnose It is therefore an object of this invention to sleeve 24 i ed overe se sleeve 2% a d provide a light weight recoil mech ni m for use isheld to a limited longitudinal reciprocation on aircraft machine gun vthereon by an annular nut 29 screwed on the Another object is to providea recoil mechanose sleeve nism that is free from natural periods ofvibra- Attached to the fecOil s e ve by hydro Weldtion, is reliable inoperation, and requires little ing are two hyd plunger units and two orno maintenance. spring units. Each unit of a pair of diametri- Stillanother object is to provide arecoilmech- Cally Opposite he o her, sothat all reacti anism for aircraft machine guns that is so placed forceswill be balanced symmetrically about the on the gun that the momentstranslated to the Q5 axis of the gun barrel- Each ype of t takesaircraft are negligible. a substantial part of the reaction forces ofthe Other objects and advantages of the invention projectile, the energybeing turned into heat in appear in the following description andclaims, the hydraulic unit and stored as energy in the which may best beunderstood when taken in sp i unitn addition to acting as a recoilconjunction with the accompanying figures, in 30 mechanism, he sprin s aCo ec which: mechanism, is preloaded, and is strong enough Figure 1 isan elevation of a machine gun proto quickly return the machine gun toits firing vided with the invention; position after recoil. Also itsupports the weight Figure 2 is a view of the re il me h ni m of themachine gun when the airplane is in a shown partially in section, takensubstantially 3.

on the line 2-2 of Figure 1; position.

Figure 3 is a longitudinal section of the meoh- Each hydraulic unitincludes a cylinder 30 anism along the line 5-43 of Figure 2; I closedat one end and hydrogen Welded to the Figure 4 isa fragmentary view insection, slmrecoil sleeve 28. The outer end of the cylinder ilar toFigure 3 showing th parts as i t d 4n is internally andcircumferentially recessed at during recoil; and 32 and communicateswith a reservoir 3% through Figure 5 is a detail of th rea guide a tube36. The reservoir is filled through a tube A machine gun mountingembodying ne for cap 39, which prevents filling of the reservoir of myinvention is shown in Figure 1, wherein a completely and leaves an airspace above the hymachine gun it, comprising a barrel member .13 draulicfluid. A piston 38 traverses the cylinder l2 and a body member M, ismounted on a wing 30, and is bored to provide an axial passage inmember56 by a rear guide 22 and a yoke l8 tersecting a cross passage by meansof which holding a recoil unit Eli. The machine gun may it communicateswith the recess 32. A variable be of any desired type or caliber.opening plate 60 is placed on the end of the The recoil unit It! is ofthe hydrospr'ing type. 5 P to and held in place by a Sp and bolt Thespring type alone is objectionable because c p s o is a ed fixedly atits e d the recoil of intermittent firing of a machine to a recoil ringd6, which is held fixed on the gun may coincide with the natural periodof a nose s ve 24 y the n A p in gland spring or a group of springs andthus bring 48 seals the piston from low pressure leakage. aboutexcessive reciprocating forces. To prevent 53 Each of the spring unitscomp a 1 this, hydraulic energy-absorbing means is emp s p elo sp 50 din a light cy ployed in conjunction with the springs. inder 52 which ishydrogen welded to the recoil The embodiment of the invention shown isso sleeve 28. The free end of the spring contacts designed that theconstruction is extremely light. a knob 54 on the recoil ring 46, whichcenters This result is achieved by fabricating the var- (so the springin its retainer.

vertical position, or accelerating in a vertical The counter-recoilbrakeor buffer mechanism of the system is of the pneumatic type formedby the offset portions of the nose and recoil sleeves upon recoil. Whenthe gun fires, the re coil sleeve is held by the yoke l8, and the nosesleeve withdrawn from it. This withdrawal creates a cavity 21 at theoffset as shown in Figure 4, and it fills with air coming in through theclearance space between the sleeves. This is an additional recoilmechanism operating on suction. Upon return to the firing position ofFigure 3, the air in the cavity is compressed and acts as a pneumaticcushion to ease the return of the gun.

The yoke [8 holds the recoil mechanism throughtrunnions 60, which are soplaced on the recoil sleeve 26 with relation to the various elements ofthe gun that the forces transmitted to the aircraft are at a minimum. Ina machine gun provided with a recoil mechanism, the forces reacting toand balancing the acceleration of the projectile are provided by therecoil mechanism, the acceleration of the gun in recoil, theacceleration of the breech bolt in the gun body, and the recoil of thegun barrel. If all these forces acted on the axis of the projectile, thegun would be in perfect equilibrium. However, the center of gravity ofthe gun and the center of gravity of the breech bolt, and the center ofresistance of the recoil mechanism are not on the axis of the projectilein the usual gun, and these forces acting through their moment armstransmit couples to the airplane carrying the gun. In modern fighting,planes carry six or eight guns in the wings and these forces are sosubstantial that in conventional mountings they tend to twist theairplane off its course.

These forcestransmittedto the airplane can be largely offset andminimized by placing the trunnions of the recoil mechanism off of theaxis of the projectile, so that opposing and nearly equal couples willbe developed that negative the reactionary couples of the guns. Thus thetrunnions of the recoil mechanism must be placed on a line closelyadjacent but above or below the axis of the projectile a determinableamount, the direction. and amount of displacement de pending upon theconstruction of the gun.

The machine gun is kept from turning in the recoil unit by a keyfastened to one sleeve and sliding in the groove of the other sleeve. Toobtain the same result, other devices may be used, such as splining thesleeves.

The body member of the gun is supported by a guide 22 shown in Figureand which allows reciprocation of the gun.

The operation of the gun is as follows. The firing position is shown inFigure 3 when the spring acts through trunnions til to hold the gunforward. When a shot is fired, a projectile is accelerated through thegun barrel, and the accelerating forces tend to move the gun to therear. The gun is reciprocated backward; the pistons 38 move down in thecylinders 38 forcing liquid through the pistons to recesses 32 fromwhence it goes up tubes 36, to the reservoir 36. Springs are compressedduring this action, storing energy used for returning the gun. The nosesleeve withdraws at the offset creating at 21 a partial vacuum whichretards the recoil of the gun. During the same time the breech bolt andthe gun barrel reciprocate in the gun body. setting up further forcesopposing the reactive forces of the projectile. These forces all combine to stop the gun after a short backward travel and the gun is thenreturned to the firing positon by springs 50.

This return movement brings into play the pneumatic cushion formed at 21by the offset of the sleeves 26 and 28. Due to this, the gun is easedinto its firing position. Also during the return stroke the pistons 30are pulled outwardly from the cylinders and the liquid returns from thereservoir. Plates 40 yield at this time so that there is littleresistance to the return of the liquid.

The recoil mechanism has been shown as applied to a gun mounted in thestructure of an airplane, but it is also applicable to a machine gunotherwise mounted-for movement, manual or otherwise. In such mounts thehandle gripped by the gunner is attached to the recoil mechanism or someother member outside of the gun system, so that the gunner will not beholdin a reciprocating member. Also, in such mounts the rear sight maybe mounted on the recoil unit, for example, on the reservoir 36. In thisway the rear sight is free of vibration which eliminates fogging'of thesights.

Although the invention has been illustrated and shown as attached to anaircraft machine gun, it is not limited to this use, or otherwiselimited, except by the terms of the following claims. r

I claim:

1. A recoil absorbing mechanism for guns comprising a stationary sleevethrough which the barrel of a gun may be inserted and held coaxially forreciprocatory movement, a hydraulic cylinder secured to either outerside of said sleeve on a plane through the axis of the sleeve, springguiding cylinders mounted on either outer side of said sleeve in adifierent plane through the axis of the sleeve, an apertured piston ineach hydraulic cylinder, a coil spring in each spring cylinder, and amember adapted to be secured to a gun to contact said pistons andsprings upon recoil of the gun.

2. A recoil absorbing mechanism for use with a gun comprising astationary sleeve within which the barrel of a gun may be coaxially heldfor reciprocation, diametrically opposed hydraulic cylinders having aclosed end and secured on the outer side of said sleeve, diametricallyopposed spring cylinders having a closed end secured to said sleeve onan axial plane different from that of the hydraulic cylinders, springsin said spring cylinders, an apertured piston traversing each hydrauliccylinder, 9. piston rod connected to each piston and sealed againstfluid leakage at the outer end of the hydraulic cylinders, a memberadapted to be secured to a gun to contact said piston rods and saidsprings upon recoil of the gun, a hydraulic reservoir mounted on saidsleeve, and conduits connecting said reservoir and each hydrauliccylinder at a point posterior to the normal position of the piston.

3. In a recoil absorbing mechanism, a gun, a gun sleeve surrounding apart of said gun, said sleeve having a large cylindrical portion to therear with respect to the gun and a small concentrio cylindrical portionto the front with respect to the gun, a stationary sleeve having largeand small diameters corresponding with those of the gun sleeve to forman air buffer, recoil absorbing means mounted on said stationary sleeve,and means connecting the gun and the recoil absorbing means whereby therecoil of the gun is absorbed by said recoil means.

J 0H1}; W. WHITE.

